Coherent demodulation implementation method for short-wave single-sideband system

Abstract

The invention provides a coherent demodulation implementation method for a short-wave single-sideband system. The coherent demodulation implementation method comprises the following steps of (1), performing SSB modulation of a sent signal at a sending end, converting the sent signal into a radio-frequency signal, and sending the radio-frequency signal into a receiving end; (2), performing filtering and down-conversion of the radio-frequency signal received by the receiving end to obtain a corresponding intermediate-frequency signal; (3), performing down-sampling of the received intermediate-frequency SSB signal with the sampling rate, which is two times of the intermediate frequency, performing 2-fold interpolation 0 of a down-sampled signal to obtain a sampled interpolated signal of the intermediate-frequency signal, and eliminating the orthogonal part of the SSB signal to obtain a DSB signal; (4), extracting a carrier phase from the DSB signal obtained by sampling interpolation by utilizing a same-phase orthogonal method, and recovering a local carrier; and (5), performing coherent demodulation of a recovered intermediate-frequency carrier. By means of the invention, the transmitting efficiency of the short-wave SSB system is increased; therefore, the SSB system can perform coherent demodulation rapidly and effectively; and furthermore, two communication parties still can communicate normally when the phase difference exists.

Description

technical field [0001] The invention relates to the field of shortwave wireless communication, in particular to a method for realizing coherent demodulation of a shortwave single sideband system. Background technique [0002] Short-wave SSB (Single Side Band, single side band signal) communication has the advantages of saving frequency band and signal power, long propagation distance, etc., and is widely used in military and civilian communication fields. Traditional SSB communication uses analog technology, which has poor application flexibility, low technical performance, single system, and poor interoperability, which restricts the further development of short-wave SSB wireless communication technology. With the popularity of programmable chip applications, based on the idea of ​​software radio, short-wave SSB analog communication can be realized digitally, which can overcome the above shortcomings of analog short-wave SSB communication. [0003] Since the envelope of th...

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Problems solved by technology

The carrier frequency of both sides of the digital shortwave single sideband SSB communication is known, but the carrier phase difference introduced during the transmission and processing process of the two sides of the communication cannot be obtained, and the SSB signal itself does not contain carrier information, and the military communication terminal requires the carrier suppression ratio of the modulated signal to reach 40dB, so the traditional carrier phase recovery algorithms—Costas ring method, inserted pilot method, square law ring method, etc. cannot directly extract carrier phase information from SSB signals, which makes the subsequent coherent demodulation digital implementation of SSB signals with here comes the difficulty

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